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  • How to validate properties across Models without repeating the validation logic

    - by Mano
    Hello All, I am building a ASP.NET Mvc app. I have a Data model say User public class user { public int userId {get; private set}; public string FirstName {get; set;} } The validation to be done is that the firstname cannot exceed 50 characters. I have another presentation model in which i have the property FirstName too. I do not want to repeat the validation logic in both the models. I want to have it in one place and that should be it. I can do it in a simpler way by adding a function which can be called while setting the property like private string firstName; public string FirstName { get { return firstName; } set { if (PropertyValidator.ValidName(value)) // assuming ValidName exists and it will throw an exception if the value is not valid { firstName = value; } } } But I am looking for something much simpler so that I do not need to add this for every property I need to have it validated. I looked at ValidationAttribute but then again I can validate this only from a controller (ModelState.IsValid). Since this model could be used by some other type of apps like console app, I could not choose that. But if there is a way to use the Mvc's ModelState.IsValid from outside of a controller, that would be awesome. Any suggestions are greatly appreciated. Thanks!!

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  • Passing models between controllers in MVC4

    - by wtfsven
    I'm in the middle of my first foray into web development with MVC4, and I've run into a problem that I just know is one of the core issues in web development in general, but can't seem to wrap my mind around it. So I have two models: Employee and Company. Employee has a Company, therefore /Employee/Create contains a field that is either a dropdown list for selecting an existing Company, or an ActionLink to /Company/Create if none exists. But here's the issue: If a user has to create a Company, I need to preserve the existing Employee model across both Views--over to /Company/Create, then back to /Employee/Create. So my first approach was to pass the Employee model to /Company/Create with a @Html.ActionLink("Add...", "Create", "Organization", Model , null), but then when I get to Company's Create(Employee emp), all of emp's values are null. The second problem is that if I try to come back to /Employee/Create, I'd be passing back an Employee, which would resolve to the POST Action. Basically, the whole idea is to save the state of the /Employee/Create page, jump over to /Company/Create to create a Company record, then back to /Employee/Create to finish creating the Employee. I know there is a well understood solution to this because , but I can't seem to phase it well enough to get a good Google result out of it. I've though about using Session, but it seems like doing so would be a bit of a kludge. I'd really like an elegant solution to this.

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  • How to refactor models without breaking WPF views?

    - by Tim Murphy
    I've just started learning WPF and like the power of databinding it presents; that is ignoring the complexity and confusion for a noob. My concern is how do you safely refactor your models/viewmodels without breaking the views that use them? Take the following snippet of a view for example: <Grid> <ListView ItemsSource="{Binding Contacts}"> <ListView.View> <GridView> <GridViewColumn Header="First Name" DisplayMemberBinding="{Binding Path=FirstName}"/> <GridViewColumn Header="Last Name" DisplayMemberBinding="{Binding Path=FirstName}"/> <GridViewColumn Header="DOB" DisplayMemberBinding="{Binding Path=DateOfBirth}"/> <GridViewColumn Header="# Pets" DisplayMemberBinding="{Binding Path=NumberOfPets}"/> <GridViewColumn Header="Male" DisplayMemberBinding="{Binding Path=IsMale}"/> </GridView> </ListView.View> </ListView> </Grid> The list is bound to the Contacts property, IList(Of Contact), of the windows DataSource and each of the properties for a Contact is bound to a GridViewColumn. Now if I change the name of the NumberOfPets property in the Contact model to PetCount the view will break. How do I prevent the view breaking?

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  • Pass List of models to controller ASP.NET MVC 5

    - by user3697231
    I have a view where user can enter some data. But problem is this: Let's say you have 3 text box on view. Every time user can fill multiple times this 3 text boxes. To clarify, let's say user fills this 3 text boxes and press button which adds on form again these 3 text boxes. Now when user clicks submit this form is sent to controller, but how do I sent List of models as parameter. My architecture for this problem is something like this: MyModel public int ID { get;set; } public string Something { get; set; } /*This three textboxes can user set multiple times*/ /*Perhaps i Can create new model with these properties and then /*put List of that model as property here, but how to fill that list inside view ??*/ public string TextBoxOneValue { get; set; } public string TextBoxTwoValue { get; set; } public string TextBoxThreeValue { get; set; } Now, i was thinking that i Create PartialView with this 3 text boxes, and then when user clicks button on view another PartialView is loaded. And now, let's say I have Two partial views loaded, and user clicks submit, how that I pass list with values of these 3 text boxes to controller ??

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  • django modelformset - one form per related table row

    - by Toby
    Hello, I have two models: class Model1(): name = CharField() url = CharField() class Model2(): model1 = ForeignKey(Model1) user = ForeignKey(User) zzz = CharField() There are 5 rows for model1 in the database, these are fixed and will rarely change. I need to display a formset for model2 that allows users to enter the zzz value, the formset must always show one form per row in the model1 table, the label for each form in the formset must be the name of the related model1. If the user deletes a model2 in the formset the next time the page loads it will render an empty zzz value for that form and the user must be able to edit the previous zzz value - meaning it must be pre populated with all model2 rows associated with the user. The idea is to print each row in the model1 table as a form instead of the user selecting the related model1 name in a select box. I know its not that complicated, but I'm seriously stumped and keep going round in circles!! Many thanks in advance. Similar to http://stackoverflow.com/questions/298779/form-or-formset-to-handle-multiple-table-rows-in-django

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  • CodeIgniter & Datamapper as frontend, Django Admin as backend, database tables inconsistent

    - by Rasiel
    I created a database for a site i'm doing using Django as the admin backend. However because the server where the site is hosted on, won't be able to support Python, I find myself needing to do the front end in PHP and as such i've decided to use CodeIgniter along with Datamapper to map the models/relationship. However DataMapper requires the tables to be in a specific format for it to work, and Django maps its tables differently, using the App name as the prefix in the table. I've tried using the prefix & join_prefix vars in datamapper but still doesn't map them correctly. Has anyone used a combination of this? and if so how have the fixed the issue of db table names being inconsistent? Is there anything out there that i can use to make them work together?

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  • django forms doubt

    - by webvulture
    Here, I am a bit confused with forms in Django. I have information for the form(a poll i.e the poll question and options) coming from some db_table - table1 or say class1 in models. Now the vote from this poll is to be captured which is another model say class2. So, I am just getting confused with the whole flow of forms, here i think. How will the data be captured into the class2 table? I was trying something like this. def blah1()     get_data_from_db_table_1()     x = blah2Form()     render_to_response(blah.html,{...})

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  • Display/Edit fields across tables in a Django Form

    - by jamida
    I have 2 tables/models, which for all practical purposes are the same as the standard Author/Book example, but with the additional restriction that in my application each Author can only write 0 or 1 books. (eg, the ForeignKey field in the Book model is or can be a OneToOneField, and there may be authors who have no corresponding book in the Book table.) I would like to be able to display a form showing multiple books and also show some fields from the corresponding Author table (eg author_name, author_address). I followed the example of the inlineformset and but that doesn't even display the author name in the generated form.

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  • Decrease DB requests number from Django templates

    - by Andrew
    I publish discount offers for my city. Offer models are passed to template ( ~15 offers per page). Every offer has lot of items(every item has FK to it's offer), thus i have to make huge number of DB request from template. {% for item in offer.1 %} {{item.descr}} {{item.start_date}} {{item.price|floatformat}} {%if not item.tax_included %}{%trans "Without taxes"%}{%endif%} <a href="{{item.offer.wwwlink}}" >{%trans "Buy now!"%}</a> </div> <div class="clear"></div> {% endfor %} So there are ~200-400 DB requests per page, that's abnormal i expect. In django code it is possible to use select_related to prepopulate needed values, how can i decrease number of requests in template?

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  • Django ORM QuerySet intersection by a field

    - by Sri Raghavan
    These are the (pseudo) models I've got. Blog: name etc... Article: name blog creator etc User (as per django.contrib.auth) So my problem is this: I've got two users. I want to get all of the articles that the two users published on the same blog (no matter which blog). I can't simply filter the Article model by both users, because that would yield the set of Articles created by both users. Obviously not what I want. but can I filter somehow to get all of the articles where a field of the object matches between the two querysets?

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  • Can django's auth_user.username be varchar(75)? How could that be done?

    - by perrierism
    Is there anything wrong with running alter table on auth_user to make username be varchar(75) so it can fit an email? What does that break if anything? If you were to change auth_user.username to be varchar(75) where would you need to modify django? Is it simply a matter of changing 30 to 75 in the source code?: username = models.CharField(_('username'), max_length=30, unique=True, help_text=_("Required. 30 characters or fewer. Letters, numbers and @/./+/-/_ characters")) Or is there other validation on this field that would have to be changed or any other repercussions to doing so? See comment discussion with bartek below regarding the reason for doing it.

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  • Problems with contenttypes when loading a fixture in Django

    - by gerdemb
    I am having trouble loading Django fixtures into my MySQL database because of contenttypes conflicts. First I tried dumping the data from only my app like this: ./manage.py dumpdata escola > fixture.json but I kept getting missing foreign key problems, because my app "escola" uses tables from other applications. I kept adding additional apps until I got to this: ./manage.py dumpdata contenttypes auth escola > fixture.json Now the problem is the following constraint violation when I try to load the data as a test fixture: IntegrityError: (1062, "Duplicate entry 'escola-t23aluno' for key 2") It seems the problem is that Django is trying to dynamically recreate contenttypes with different primary key values that conflict with the primary key values from the fixture. This appears to be the same as bug documented here: http://code.djangoproject.com/ticket/7052 The problem is that the recommended workaround is to dump the contenttypes app which I'm already doing!? What gives? If it makes any difference I do have some custom model permissions as documented here: http://docs.djangoproject.com/en/dev/ref/models/options/#permissions

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  • How do I memoize expensive calculations on Django model objects?

    - by David Eyk
    I have several TextField columns on my UserProfile object which contain JSON objects. I've also defined a setter/getter property for each column which encapsulates the logic for serializing and deserializing the JSON into python datastructures. The nature of this data ensures that it will be accessed many times by view and template logic within a single Request. To save on deserialization costs, I would like to memoize the python datastructures on read, invalidating on direct write to the property or save signal from the model object. Where/How do I store the memo? I'm nervous about using instance variables, as I don't understand the magic behind how any particular UserProfile is instantiated by a query. Is __init__ safe to use, or do I need to check the existence of the memo attribute via hasattr() at each read? Here's an example of my current implementation: class UserProfile(Model): text_json = models.TextField(default=text_defaults) @property def text(self): if not hasattr(self, "text_memo"): self.text_memo = None self.text_memo = self.text_memo or simplejson.loads(self.text_json) return self.text_memo @text.setter def text(self, value=None): self.text_memo = None self.text_json = simplejson.dumps(value)

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  • Django: How to create a model dynamically just for testing

    - by muhuk
    I have a Django app that requires a settings attribute in the form of: RELATED_MODELS = ('appname1.modelname1.attribute1', 'appname1.modelname2.attribute2', 'appname2.modelname3.attribute3', ...) Then hooks their post_save signal to update some other fixed model depending on the attributeN defined. I would like to test this behaviour and tests should work even if this app is the only one in the project (except for its own dependencies, no other wrapper app need to be installed). How can I create and attach/register/activate mock models just for the test database? (or is it possible at all?) Solutions that allow me to use test fixtures would be great.

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  • Complex Django filter question

    - by HWM-Rocker
    Lets say I have this class (simplified): class Tag (...): children = models.ManyToManyField(null=True, symmetrical=False) Now I already implemented the functions get_parents, get_all_ancestors. Is there a nice pythonic way to just the top level tags? If I had designed my Tags differently (to point to the parents instead) I would just make get_all_parents().filter(children=null). My first thought is to create a new function that will go recursively through all parents and save those that has none. But is there a possibility with filters or Query-objects to do the same (with fewer lines of code)? Thanks for your help. [edit] When it is finished, it should be a hierarchical tagging system. Each tag can have children, parents, but only the children are saved. I want to get all the top level tags, that point through many children / childrens children to my tag.

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  • Problem with migrating a model in ruby

    - by Shreyas Satish
    I run script/generate model query edit query.rb in models.. class Query < ActiveRecord::Base #I even tried Migrations instead of Base def sef.up create table :queries do|t| t.string :name end end def self.down drop_table :queries end end ,run rake db:migrate. and what I see in db is this: mysql> desc queries; +------------+----------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +------------+----------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | created_at | datetime | YES | | NULL | | | updated_at | datetime | YES | | NULL | | +------------+----------+------+-----+---------+----------------+ Where is the "name" field? HELP ! Cheers !

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  • How do I find the "concrete class" of a django model baseclass

    - by Mr Shark
    I'm trying to find the actual class of a django-model object, when using model-inheritance. Some code to describe the problem: class Base(models.model): def basemethod(self): ... class Child_1(Base): pass class Child_2(Base): pass If I create various objects of the two Child classes and the create a queryset containing them all: Child_1().save() Child_2().save() (o1, o2) = Base.objects.all() I want to determine if the object is of type Child_1 or Child_2 in basemethod, I can get to the child object via o1.child_1 and o2.child_2 but that reconquers knowledge about the childclasses in the baseclass. I have come up with the following code: def concrete_instance(self): instance = None for subclass in self._meta.get_all_related_objects(): acc_name = subclass.get_accessor_name() try: instance = self.__getattribute__(acc_name) return instance except Exception, e: pass But it feels brittle and I'm not sure of what happens when if I inherit in more levels.

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  • Model objects versions in Django

    - by pablo
    Hi I'm building an e-commerce website. I have a Product and Order models. It's possible that a customer order a product and then the admin change its price or other fields before the customer actually get it. A possible solution is to add a 'version' field to the Product model. When the admin update a product field I'll add a timestamp and create a new object instead of updating the old one. An Order will have a reference to a specific product version. Does this make sense? Will overriding the Product Save method be sufficient to make it work? Thanks

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  • Can django lazy-load fields in a model?

    - by Leopd
    One of my django models has a large TextField which I often don't need to use. Is there a way to tell django to "lazy-load" this field? i.e. not to bother pulling it from the database unless I explicitly ask for it. I'm wasting a lot of memory and bandwidth pulling this TextField into python every time I refer to these objects. The alternative would be to create a new table for the contents of this field, but I'd rather avoid that complexity if I can.

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  • CakePHP HABTM Plugin table naming conventions (for 1.3)

    - by Parris
    Hi everyone, I know naming conventions for tables used by plugins generally start with the name of the plugin and then the model pluralized. For example lets say I had a plugin called Poll, with a model also called PollPoll and another model called PollTag then the resulting table names would be poll_polls and poll_tags. They would also have a habtm relationship so what is the convention for that table name? I believe it would poll_poll_polls_poll_tags, although it is a little redundant it makes sense since the first poll_ represents the name of the plugin, while poll_polls and poll_tags relates to the models. Also have any naming conventions changed for plugins in 1.3? Is the above stated correct? Thanks!

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  • Ruby on Rails: Simple way to select all records of a nested model?

    - by Josh Pinter
    Just curious, I spent an embarrassing amount of time trying to get an array of all the records in a nested model. I just want to make sure there is not a better way. Here is the setup: I have three models that are nested under each other (Facilities Tags Inspections), producing code like this for routes.rb: map.resources :facilities do |facilities| facilities.resources :tags, :has_many => :inspections end I wanted to get all of the inspections for a facility and here is what my code ended up being: def facility_inspections @facility = Facility.find(params[:facility_id]) @inspections = [] @facility.tags.each do |tag| tag.inspections.each do |inspection| @inspections << inspection end end end It works but is this the best way to do this - I think it's cumbersome. Thanks in advance. Josh

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  • Saving related model objects

    - by iHeartDucks
    I have two related models (one to many) in my django app and When I do something like this ObjBlog = Blog() objBlog.name = 'test blog' objEntry1 = Entry() objEntry1.title = 'Entry one' objEntry2 = Entry() objEntry2.title = 'Entry Two' objBlog.entry_set.add(objEntry1) objBlog.entry_set.add(objEntry2) I get an error which says "null value in column and it violates the foreign key not null constraint". None of my model objects have been saved. Do I have to save the "objBlog" before I could set the entries? I was hoping I could call the save method on objBlog to save it all. NOTE: I am not creating a blog engine and this is just an example.

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  • x86 and Memory Addressing

    - by IM
    I've been reading up on memory models in an assembly book I picked up and I have a question or two. Let's say that the address bus has 32 lines, the data bus has 32 lines and the CPU is 32-bit (for simplicity). Now if the CPU makes a read request and sends the 32bit address, but only needs 8 bits, all 32 bits come back anyway? Also, the addresses in memory are still addressed per byte correct? So fetching one byte would bring back 0000 0001 to address 0000 0004? Thanks in advance

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  • How do I check for Existence of a Record in GAE

    - by VDev
    I am trying to create a simple view in Django & GAE, which will check if the user has a profile entity and prints a different message for each case. I have the program below, but somehow GAE always seem to return a object. My program is below import datetime from django.http import HttpResponse, HttpResponseRedirect from google.appengine.api import users from google.appengine.ext import db from models import Profile import logging #from accounts.views import profile # Create your views here. def login_view(request): user = users.get_current_user() profile = db.GqlQuery("SELECT * FROM Profile WHERE account = :1", users.get_current_user()) logging.info(profile) logging.info(user) if profile: return HttpResponse("Congratulations Your profile is already created.") else: return HttpResponse("Sorry Your profile is NOT created.") My model object is Profile defined as follows: class Profile(db.Model): first_name = db.StringProperty() last_name = db.StringProperty() gender = db.StringProperty(choices=set(["Male", "Female"])) account = db.UserProperty(required = True) friends = db.ListProperty(item_type=users.User) last_login = db.DateTimeProperty(required=True) Thanks for the help.

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  • User HasOne ActiveToken, HasMany Tokens, how to setup in Rails?

    - by viatropos
    I have two simple models: class User < ActiveRecord::Base has_many :tokens # has_one doesn't work, because Token already stores # foreign id to user... # has_one :active_token, :class_name => "Token" # belongs_to doesn't work because Token belongs to # User already, and they both can't belong to each other # belongs_to :active_token, :class_name => "Token" end class Token < ActiveRecord::Base belongs_to :user end I want to say "User has_one :active_token, :class_name => 'Token'", but I can't because Token already belongs_to User. What I did instead was just manually add similar functionality to the user like so: class User < ActiveRecord::Base has_many :tokens attr_accessor :active_token after_create :save_active_token before_destroy :destroy_active_token # it belongs_to, but you can't have both belongs_to each other... def active_token return nil unless self.active_token_id @active_token ||= Token.find(self.active_token_id) end def active_token=(value) self.active_token_id = value.id @active_token = value end def save_active_token self.active_token.user = self self.active_token.save end def destroy_active_token self.active_token.destroy if self.active_token end end Is there a better way?

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